Multi-step hydraulic power mechanism



Aug- 12,1969 H. E. BRANSON 3,460,346

MULTI-STEP HYDRAULIC POWER MECHANISM Filed Oct. 5. 1967 f I" ff J 2 25/21 o I 2 3,460,346 MULTI-STEP HYDRAULIC POWER MECHANISM Henry E.Branson, deceased, late of Lincolnwood, Ill., 'by Esther E. Branson,executrix, Lincolnwood, Ill., assignor to Stromberg Hydraulic Brake andCoupling Company, Chicago, Ill., a corporation of Illinois Filed Oct. 5,1967, Ser. No. 674,699 Int. Cl. Fb 7/00, 7/08 U.S. Cl. 60-54.5 1 ClaimABSTRACT 0F THE DISCLOSURE A hydraulic cylinder contains a reciprocatingpiston which as it reciprocates forces hydraulic uid from the cylinderthrough a check valve to a hydraulically actuated element to cause aseries of step by step movements thereof. A reservoir supplies hydraulicuid to the cylinder after each piston movement. The system includesmeans for forcing a return of the hydraulic fluid back through thecylinder to the reservoir when the check valve is opened.

SUMMARY OF THE INVENTION This invention relates to a hydraulic powermechanism. It has one object, to provide a power source which, under thecontrol of the operator will, first, apply a series of hydraulicimpulses to a closed hydraulic system, the impulses resulting in a stepby step forward movement of a mechanical element. And second, it willprovide means subject to the will of the operator to apply retrogrademovement to the mechanical element and return the hydraulic uid to thepower source.

The invention is, for convenience, illustrated as applied to a step bystep automotive vehicle transmission, but may equally well be used forother purposes.

Other objects will appear from time to time throughout the specificationand claim.

DESCRIPTION OF THE DRAWINGS Referring to the drawings:

FIGURE l is a view of the power source;

FIGURE 2 is a side elevation of FIGURE '1;

FIGURE 3 is a section along the line 3-3 of FIG- URE 3;

FIGURE 4 is a diagrammatic illustration of the hydraulically actuatedmechanical element.

DESCRIPTION OF THE PREFERRED EMBODI- MENTS OF THE INVENTION Referring toFIGURES 1 and 2, the base 1 supports a cylinder 2. The latter carries ahydraulic fluid reservoir 3 which may be integral with or removabletherefrom and may be filled through a filler cap 4. A fulcrum pin Ssupported in the flanges 6 projecting upwardly from the base 1 carriesrotatably mounted thereon a sleeve 7 from which projects a lever arm 8carrying a pedal `9. Sleeve 7 also carries a lever arm 10 to which ispivoted a piston rod 11 which penetrates the open end of the cylinder 2,being enclosed by an elastomeric bellows 12 to protect the open-endedcylinder 2 from dust and dirt.

A wall of the cylinder 2 is ported to communicate with the reservoir 3.The skirted piston 14 is slidable in the cylinder 2 and carrieselastomeric packing sleeves 15 and 16 on each skirt, the piston rod 11being loosely socketed in the recess 17 in the closed end of the piston.The piston is held within the cylinder at its outer skirt by snap ringor piston stop 18.

The piston is slotted at 19 in communication with the annular chamber 20between the end skirts of the piston and the cylinder in communicationwith the makeup port Frice leading to the reservoir. A pin 21 isthreaded in the wall of the cylinder to penetrate the slot 19. The slotpermits movement of the piston longitudinally with respect to the pin21. The piston 14 at its forward end is ported at 22 in communicationwith the slot 19. A ball valve 23 may be seated by valve spring 24.Return spring 25 biases the piston in upstream position toward the stop18 as shown in FIGURE 3 to hold the ball valve 23I against the pin 21 toopen the port 22.

The cylinder 2 is ported on the downstream side of the piston at 26 tocommunicate with the hydraulic duct 27 which leads to a check valvehousing 28.

In the position shown in FIGURE 3, there is a free hydraulic fluid pathfrom reservoir 3 through the make-up port, chamber 20, slot 19, port 22,to the downstream end of the cylinder, thence through the port 26through duct 27 to the check valve housing 28.

When the pedal 9 is depressed, the lever 1()A rocks to move the pistonrod 11 and the piston 14 to the left. This permits the valve spring 24to seat the valve, closing the passage between the downstream end of thecylinder and the reservoir. Each separate rotation of the lever 8compresses the return spring 25 and, because the valve 23 is seated,forces a slug of hydraulic fluid through the duct 27 into the checkvalve housing 28 and out through the duct 29. When the operator releasesthe pedal 9, the return spring 25 forces the piston back into theposition shown in FIGURE 3 and, because check valve 28 inhibitshydraulic flow back through duct 27, a vacuum is created in the cylinderand draws make-up hydraulic fluid from the reservoir into the downstreamportion of the cylinder to replace the slug previously dischargedthrough the check valve. The capacity of the reservoir may vary, but itmust always hold enough hydraulic uid to satisfy the number of strokesof the piston contemplated.

A suitable use for this device can well be a step by step automotivevehicle transmission.

The duct 29 leads to a slave cylinder 30 containing a piston 31, whichdrives through a rod 32, a rack 33, and when moved to the leftcompresses a return spring 34. Gear 35 meshes with the rack 32 and ismounted on a shaft 36 which is the control shaft of the automotivetransmission.

Assuming that this is a tive step automotive transmission, each slug ofhydraulic fluid forced into the cylinder 30 rotates the transmissionshaft for one step. The check valve 28 locks the incompressiblehydraulic fluid in the system to hold the transmission shaft inposition. It cannot return and the spring 34 is strong enough to inhibitfurther forward movement of the rack. The next time the pedal isdepressed, another slug of hydraulic fluid is forced through check valve28 to move the transmission a step forward. This step by step operationcontinues until the last step is reached, at which time the spring 34would bottom to serve as a stop to prevent further forward movement ofrack 32.

When the operator wishes to return to the starting position, he pullsthe control wire 37, with the cylinder in the position shown in FIGURE 3and this rotates the lever 38 to unseat the check valve 28. The spring33 biases the piston 30 in the return direction to force the hydraulicfluid back through the check valve and the cylinder through the valve 23held open by the pin 21 into the reservoir.

The cylinder 2 is thus ported in register with the reservoir for intakeand in register with duct 27 for exhaust under forward power operationof the piston. However, intake and exhaust functions of the ports arereversed when the spring 34 actuating the piston 31 forces the hydraulicfluid into the cylinder 2 through the piston 14 and out into thereservoir.

What is claimed is:

1. A power system including a manually actuated hydraulic mastercylinder closed at one end and open at the other, containing a skirtedpiston, a piston stop in the outer end of the cylinder, a return springbiasing the piston against the stop, a piston rod, a manually actuatedlever adapted to drive the piston away from the stop against the returnspring to generate hydraulic pressure in the cylinder, the piston beinglongitudinally slotted and the end thereof nearest the return springbeing ported in register with the slot, a valve biased to close theport, a pin projecting from the wall of the cylinder into the slot sopositioned that it engages and unseats the valve when the piston is heldagainst the stop, a make-up reservoir, a free hydraulic connectionbetween it and the annular chamber defined by the skirts, the cylinderand the piston, the slot being open to said chamber, an outlet portleading from the return spring end of the cylinder, a slave cylinder, aduct between it and the outlet port, a manually releasable check valvein the duct biased to inhibit return of hydraulic fluid from the slaveto the References Cited UNITED STATES PATENTS 2,649,692 8/1953 `Stelzer60-54.6 2,817,955 .l2/1957 Mercier 60-545 2,847,827 8/ 1958 Johnson60-54.6 3,204,413 9/1965 Pace 60-54.5 3,221,502 12/ 1965 Shellhausc60-54.6

MARTIN P. SCHWADRON, Primary Examiner ROBERT R. BUNEVICH, AssistantExaminer U.S. Cl. X.R.

